GO:0140123 negative regulation of Lewy body formation

Lewy bodies are abnormal intraneuronal protein aggregates that represent the pathological hallmark of Parkinson's disease (PD), dementia with Lewy bodies (DLB), and other synucleinopathies. These inclusions are primarily composed of misfolded and aggregated alpha-synuclein (SNCA), a presynaptic protein whose conformational transition from a soluble monomer to insoluble fibrils underlies disease pathogenesis. The Gene Ontology term GO:0140123, negative regulation of Lewy body formation, encompasses any cellular process that stops, prevents, or reduces the frequency, rate, or extent of Lewy body formation. This regulatory process is of paramount importance because it represents a potential therapeutic target: enhancing the cell's natural capacity to prevent or clear Lewy body pathology could slow or halt neurodegeneration. Research into negative regulation of Lewy body formation has revealed multiple intersecting pathways. Autophagic clearance mechanisms, particularly macroautophagy and chaperone-mediated autophagy, are central to the degradation of alpha-synuclein aggregates. The transcription factor TFEB (transcription factor EB) acts as a master regulator of the autophagy-lysosomal pathway, and its subcellular localization is altered in nigral neurons of subjects with Lewy body diseases, suggesting that impaired TFEB function contributes to pathology. Additionally, the Nrf2-Keap1 pathway provides neuroprotection by upregulating antioxidant response elements and reducing oxidative stress that promotes alpha-synuclein aggregation. Post-translational modifications and protein-protein interactions also modulate Lewy body formation. The prolyl-isomerase Pin1 accumulates in Lewy bodies and facilitates the formation of alpha-synuclein inclusions, indicating that Pin1 activity may counteract negative regulatory processes. Conversely, beta-synuclein (SNCB) blocks alpha-synuclein condensate fusion and disrupts the maturation of phase-separated droplets, thereby acting as a negative regulator of Lewy body formation. Polo-like kinase 2 (PLK2) has been shown to disrupt autophagic flux and promote SNCA pathology, suggesting that inhibition of PLK2 could enhance negative regulation of Lewy body formation. These findings collectively highlight the complexity of the regulatory network and the need for precise experimental models to dissect causal relationships.

GO:0140123, negative regulation of Lewy body formation, is a biological process term defined as any process that stops, prevents, or reduces the frequency, rate, or extent of Lewy body formation. In practical terms, it refers to the cellular mechanisms that counteract the assembly of alpha-synuclein into the large, fibrillar inclusions known as Lewy bodies. This includes processes that inhibit alpha-synuclein aggregation, promote the clearance of alpha-synuclein oligomers or fibrils, or maintain alpha-synuclein in its soluble, functional state.

Negative regulation of Lewy body formation is critically important because Lewy bodies are the defining pathological feature of Parkinson's disease and related synucleinopathies, affecting millions of people worldwide. Understanding the molecular mechanisms that prevent or reduce Lewy body formation provides a rational basis for developing disease-modifying therapies. Unlike symptomatic treatments that only manage motor symptoms, targeting the processes that negatively regulate Lewy body formation could potentially halt or slow neurodegeneration. Furthermore, identifying the genes and pathways involved in this regulatory process can reveal biomarkers for early diagnosis and novel drug targets.

The following genes and proteins are critically involved in the negative regulation of Lewy body formation, based on published experimental evidence.

The negative regulation of Lewy body formation is controlled by multiple intersecting signaling pathways. The mTOR pathway is a major negative regulator of autophagy; inhibition of mTOR (e.g., by rapamycin) enhances autophagic flux and promotes clearance of alpha-synuclein aggregates, thereby enhancing negative regulation of Lewy body formation. Conversely, activation of mTOR suppresses autophagy and favors Lewy body formation. The TFEB-mediated transcriptional program is a downstream target of mTOR and serves as a master switch for the autophagy-lysosomal pathway. The Nrf2-Keap1 pathway regulates the antioxidant response and indirectly influences Lewy body formation by modulating oxidative stress. Additionally, PLK2 negatively regulates autophagic flux, and its inhibition restores autophagic clearance. MicroRNAs provide an additional layer of post-transcriptional regulation by targeting SNCA mRNA. These regulatory mechanisms collectively determine the balance between alpha-synuclein aggregation and clearance.

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are the most common synucleinopathies, characterized by the presence of Lewy bodies in surviving neurons. The negative regulation of Lewy body formation is impaired in these diseases, leading to alpha-synuclein accumulation and neurodegeneration. Genetic mutations in GBA, LRRK2, and SNCA increase the risk of PD and are associated with impaired autophagic clearance and enhanced aggregation. TFEB dysfunction has been observed in nigral neurons of subjects with sporadic and GBA-related Lewy body diseases, suggesting that compromised TFEB-mediated autophagy contributes to pathology. Therapeutic strategies aimed at enhancing negative regulation of Lewy body formation, such as TFEB activation or PLK2 inhibition, are under investigation.

Multiple system atrophy (MSA) is another synucleinopathy characterized by glial cytoplasmic inclusions composed of alpha-synuclein. While the cellular context differs from PD, the fundamental process of alpha-synuclein aggregation and its negative regulation is relevant. The amyloid state of proteins, including alpha-synuclein, is a common feature across these diseases. Understanding the mechanisms that negatively regulate Lewy body formation in neurons may also inform strategies for MSA, although the cell types involved are different.

Mutations in the GBA gene, encoding glucocerebrosidase, are the most common genetic risk factor for Parkinson's disease and Lewy body dementia. GBA mutations impair lysosomal function, leading to reduced autophagic clearance of alpha-synuclein and enhanced Lewy body formation. Studies have shown altered TFEB subcellular localization in nigral neurons of subjects with GBA-related Lewy body diseases, linking lysosomal dysfunction to impaired negative regulation of Lewy body formation. This provides a strong rationale for therapies that activate TFEB or enhance lysosomal function in GBA mutation carriers.

Recent single-nucleus RNA sequencing studies have unveiled relationships between microglia and endothelial cells in mixed Alzheimer's disease and vascular pathology, which often co-occurs with Lewy body pathology. Although the primary focus is on Alzheimer's disease, the interaction between microglia and endothelial cells may influence the brain's ability to negatively regulate Lewy body formation through inflammatory and vascular mechanisms. This highlights the importance of considering multicellular interactions in neurodegenerative diseases.

Genome-wide CRISPR knockout or activation screens can identify genes that negatively regulate Lewy body formation. By using alpha-synuclein aggregation as a readout, researchers can uncover novel regulators. For example, a CRISPR screen could identify PLK2 as a negative regulator of autophagic flux, whose knockout enhances clearance. Similarly, screens can identify genes in the TFEB pathway or Nrf2 pathway that modulate aggregation. These screens are typically performed in cell lines expressing fluorescently tagged alpha-synuclein, followed by flow cytometry or imaging to quantify aggregates.

Mass spectrometry-based proteomics can identify proteins that interact with alpha-synuclein or that are differentially expressed during negative regulation of Lewy body formation. Co-immunoprecipitation followed by mass spectrometry can reveal binding partners such as SNCB, Pin1, or chaperones. Quantitative proteomics of Lewy body-enriched fractions from patient brains can identify disease-specific changes. These approaches provide unbiased insights into the molecular machinery involved.

Live-cell imaging using fluorescently tagged alpha-synuclein can monitor the formation and dissolution of condensates in real time. Phase separation assays, such as those using polyethylene glycol (PEG) or dextran, can reconstitute condensate formation in vitro. These methods allow researchers to test whether a candidate gene product (e.g., SNCB) blocks condensate fusion or maturation. Advanced techniques like fluorescence recovery after photobleaching (FRAP) can measure the dynamics of alpha-synuclein within condensates.

Autophagic flux can be measured using tandem fluorescent LC3 reporters (e.g., mCherry-GFP-LC3) or by monitoring the degradation of autophagic substrates such as p62/SQSTM1. TFEB nuclear translocation can be assessed by immunofluorescence or subcellular fractionation. These assays are critical for determining whether a genetic or pharmacological intervention enhances negative regulation of Lewy body formation through autophagic clearance.

Researchers studying negative regulation of Lewy body formation-related genes often need to determine whether a candidate gene is causally involved in preventing alpha-synuclein aggregation or enhancing its clearance. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research, from gene knockout to precise point mutations and knock-in models.

The negative regulation of Lewy body formation (GO:0140123) is a critical biological process that counteracts the aggregation of alpha-synuclein into Lewy bodies, the pathological hallmark of Parkinson's disease and related synucleinopathies. Research has identified multiple regulatory mechanisms, including inhibition of phase separation by beta-synuclein, enhancement of autophagic clearance via TFEB, and modulation of oxidative stress by Nrf2. These pathways offer promising therapeutic targets for disease modification. Continued investigation using CRISPR-based models and advanced screening technologies will further elucidate the molecular players and pave the way for novel treatments.